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<h1 class="title">main.cpp 示例文件</h1>
<span class="subtitle">demos/photosurface/main.cpp</span>
<!-- $$$demos/photosurface/main.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp">

  <span class="comment">/****************************************************************************
  **
  ** Copyright (C) 2017 The Qt Company Ltd.
  ** Contact: https://www.qt.io/licensing/
  **
  ** This file is part of the examples of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:BSD$
  ** Commercial License Usage
  ** Licensees holding valid commercial Qt licenses may use this file in
  ** accordance with the commercial license agreement provided with the
  ** Software or, alternatively, in accordance with the terms contained in
  ** a written agreement between you and The Qt Company. For licensing terms
  ** and conditions see https://www.qt.io/terms-conditions. For further
  ** information use the contact form at https://www.qt.io/contact-us.
  **
  ** BSD License Usage
  ** Alternatively, you may use this file under the terms of the BSD license
  ** as follows:
  **
  ** &quot;Redistribution and use in source and binary forms, with or without
  ** modification, are permitted provided that the following conditions are
  ** met:
  **   * Redistributions of source code must retain the above copyright
  **     notice, this list of conditions and the following disclaimer.
  **   * Redistributions in binary form must reproduce the above copyright
  **     notice, this list of conditions and the following disclaimer in
  **     the documentation and/or other materials provided with the
  **     distribution.
  **   * Neither the name of The Qt Company Ltd nor the names of its
  **     contributors may be used to endorse or promote products derived
  **     from this software without specific prior written permission.
  **
  **
  ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  ** &quot;AS IS&quot; AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.&quot;
  **
  ** $QT_END_LICENSE$
  **
  ****************************************************************************/</span>

  <span class="preprocessor">#ifdef QT_WIDGETS_LIB</span>
  <span class="preprocessor">#include &lt;QtWidgets/QApplication&gt;</span>
  <span class="preprocessor">#else</span>
  <span class="preprocessor">#include &lt;QtGui/QGuiApplication&gt;</span>
  <span class="preprocessor">#endif</span>
  <span class="preprocessor">#include &lt;QtQml/QQmlApplicationEngine&gt;</span>
  <span class="preprocessor">#include &lt;QtQml/QQmlContext&gt;</span>
  <span class="preprocessor">#include &lt;QtQuick/QQuickWindow&gt;</span>
  <span class="preprocessor">#include &lt;QtGui/QImageReader&gt;</span>
  <span class="preprocessor">#include &lt;QtCore/QCommandLineParser&gt;</span>
  <span class="preprocessor">#include &lt;QtCore/QCommandLineOption&gt;</span>
  <span class="preprocessor">#include &lt;QtCore/QDebug&gt;</span>
  <span class="preprocessor">#include &lt;QtCore/QDir&gt;</span>
  <span class="preprocessor">#include &lt;QtCore/QMimeDatabase&gt;</span>
  <span class="preprocessor">#include &lt;QtCore/QStandardPaths&gt;</span>
  <span class="preprocessor">#include &lt;QtCore/QUrl&gt;</span>

  <span class="keyword">static</span> <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span> imageNameFilters()
  {
      <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span> result;
      <span class="type"><a href="../qtcore/qmimedatabase.html">QMimeDatabase</a></span> mimeDatabase;
      <span class="keyword">const</span> <span class="keyword">auto</span> supportedMimeTypes <span class="operator">=</span> <span class="type"><a href="../qtgui/qimagereader.html">QImageReader</a></span><span class="operator">::</span>supportedMimeTypes();
      <span class="keyword">for</span> (<span class="keyword">const</span> <span class="type"><a href="../qtcore/qbytearray.html">QByteArray</a></span> <span class="operator">&amp;</span>m : supportedMimeTypes) {
          <span class="keyword">const</span> <span class="keyword">auto</span> suffixes <span class="operator">=</span> mimeDatabase<span class="operator">.</span>mimeTypeForName(m)<span class="operator">.</span>suffixes();
          <span class="keyword">for</span> (<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&amp;</span>suffix : suffixes)
              result<span class="operator">.</span>append(QLatin1String(<span class="string">&quot;*.&quot;</span>) <span class="operator">+</span> suffix);
      }
      <span class="keyword">return</span> result;
  }

  <span class="type">int</span> main(<span class="type">int</span> argc<span class="operator">,</span> <span class="type">char</span><span class="operator">*</span> argv<span class="operator">[</span><span class="operator">]</span>)
  {
      <span class="comment">// The reason to use QApplication is that QWidget-based dialogs</span>
      <span class="comment">// are the native dialogs on Qt-based platforms like KDE,</span>
      <span class="comment">// but they cannot be instantiated if this is a QGuiApplication.</span>
  <span class="preprocessor">#ifdef QT_WIDGETS_LIB</span>
      <span class="type"><a href="../qtwidgets/qapplication.html">QApplication</a></span> app(argc<span class="operator">,</span> argv);
  <span class="preprocessor">#else</span>
      <span class="type"><a href="../qtgui/qguiapplication.html">QGuiApplication</a></span> app(argc<span class="operator">,</span> argv);
  <span class="preprocessor">#endif</span>
      <span class="type"><a href="qquickwindow.html">QQuickWindow</a></span><span class="operator">::</span>setDefaultAlphaBuffer(<span class="keyword">true</span>);

      <span class="type"><a href="../qtcore/qcoreapplication.html">QCoreApplication</a></span><span class="operator">::</span>setApplicationName(<span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">&quot;Photosurface&quot;</span>));
      <span class="type"><a href="../qtcore/qcoreapplication.html">QCoreApplication</a></span><span class="operator">::</span>setOrganizationName(<span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">&quot;QtProject&quot;</span>));
      <span class="type"><a href="../qtcore/qcoreapplication.html">QCoreApplication</a></span><span class="operator">::</span>setApplicationVersion(QLatin1String(QT_VERSION_STR));
      <span class="type"><a href="../qtcore/qcommandlineparser.html">QCommandLineParser</a></span> parser;
      parser<span class="operator">.</span>setApplicationDescription(<span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">&quot;Qt Quick Demo - Photo Surface&quot;</span>));
      parser<span class="operator">.</span>addHelpOption();
      parser<span class="operator">.</span>addVersionOption();
      parser<span class="operator">.</span>addPositionalArgument(<span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">&quot;directory&quot;</span>)<span class="operator">,</span>
                                   <span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">&quot;The image directory or URL to show.&quot;</span>));
      parser<span class="operator">.</span>process(app);

      <span class="type"><a href="../qtcore/qurl.html">QUrl</a></span> initialUrl;
      <span class="keyword">if</span> (<span class="operator">!</span>parser<span class="operator">.</span>positionalArguments()<span class="operator">.</span>isEmpty()) {
          initialUrl <span class="operator">=</span> <span class="type"><a href="../qtcore/qurl.html">QUrl</a></span><span class="operator">::</span>fromUserInput(parser<span class="operator">.</span>positionalArguments()<span class="operator">.</span>first()<span class="operator">,</span>
                                           <span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>currentPath()<span class="operator">,</span> <span class="type"><a href="../qtcore/qurl.html">QUrl</a></span><span class="operator">::</span>AssumeLocalFile);
          <span class="keyword">if</span> (<span class="operator">!</span>initialUrl<span class="operator">.</span>isValid()) {
              <a href="../qtcore/qtglobal.html#qWarning">qWarning</a>()<span class="operator">.</span>nospace() <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;Invalid argument: \&quot;&quot;</span>
                  <span class="operator">&lt;</span><span class="operator">&lt;</span> parser<span class="operator">.</span>positionalArguments()<span class="operator">.</span>first() <span class="operator">&lt;</span><span class="operator">&lt;</span> <span class="string">&quot;\&quot;: &quot;</span> <span class="operator">&lt;</span><span class="operator">&lt;</span> initialUrl<span class="operator">.</span>errorString();
              <span class="keyword">return</span> <span class="number">1</span>;
          }
      }

      <span class="keyword">const</span> <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span> nameFilters <span class="operator">=</span> imageNameFilters();

      <span class="type"><a href="../qtqml/qqmlapplicationengine.html">QQmlApplicationEngine</a></span> engine;
      <span class="type"><a href="../qtqml/qqmlcontext.html">QQmlContext</a></span> <span class="operator">*</span>context <span class="operator">=</span> engine<span class="operator">.</span>rootContext();

      <span class="type"><a href="../qtcore/qurl.html">QUrl</a></span> picturesLocationUrl <span class="operator">=</span> <span class="type"><a href="../qtcore/qurl.html">QUrl</a></span><span class="operator">::</span>fromLocalFile(<span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>homePath());
      <span class="keyword">const</span> <span class="type"><a href="../qtcore/qstringlist.html">QStringList</a></span> picturesLocations <span class="operator">=</span> <span class="type"><a href="../qtcore/qstandardpaths.html">QStandardPaths</a></span><span class="operator">::</span>standardLocations(<span class="type"><a href="../qtcore/qstandardpaths.html">QStandardPaths</a></span><span class="operator">::</span>PicturesLocation);
      <span class="keyword">if</span> (<span class="operator">!</span>picturesLocations<span class="operator">.</span>isEmpty()) {
          picturesLocationUrl <span class="operator">=</span> <span class="type"><a href="../qtcore/qurl.html">QUrl</a></span><span class="operator">::</span>fromLocalFile(picturesLocations<span class="operator">.</span>first());
          <span class="keyword">if</span> (initialUrl<span class="operator">.</span>isEmpty()
              <span class="operator">&amp;</span><span class="operator">&amp;</span> <span class="operator">!</span><span class="type"><a href="../qtcore/qdir.html">QDir</a></span>(picturesLocations<span class="operator">.</span>first())<span class="operator">.</span>entryInfoList(nameFilters<span class="operator">,</span> <span class="type"><a href="../qtcore/qdir.html">QDir</a></span><span class="operator">::</span>Files)<span class="operator">.</span>isEmpty()) {
              initialUrl <span class="operator">=</span> picturesLocationUrl;
          }
      }

      context<span class="operator">-</span><span class="operator">&gt;</span>setContextProperty(<span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">&quot;contextPicturesLocation&quot;</span>)<span class="operator">,</span> picturesLocationUrl);
      context<span class="operator">-</span><span class="operator">&gt;</span>setContextProperty(<span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">&quot;contextInitialUrl&quot;</span>)<span class="operator">,</span> initialUrl);
      context<span class="operator">-</span><span class="operator">&gt;</span>setContextProperty(<span class="type"><a href="../qtcore/qstring.html#QStringLiteral">QStringLiteral</a></span>(<span class="string">&quot;contextImageNameFilters&quot;</span>)<span class="operator">,</span> nameFilters);

      engine<span class="operator">.</span>load(<span class="type"><a href="../qtcore/qurl.html">QUrl</a></span>(<span class="string">&quot;qrc:///photosurface.qml&quot;</span>));
      <span class="keyword">if</span> (engine<span class="operator">.</span>rootObjects()<span class="operator">.</span>isEmpty())
          <span class="keyword">return</span> <span class="operator">-</span><span class="number">1</span>;

      <span class="keyword">return</span> app<span class="operator">.</span>exec();
  }

</pre>
</div>
<!-- @@@demos/photosurface/main.cpp -->
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   their respective owners.<br>    The documentation provided herein is licensed under the terms of the    <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation    License version 1.3</a> as published by the Free Software Foundation.<br>    Qt and respective logos are trademarks of The Qt Company Ltd.     in Finland and/or other countries worldwide. All other trademarks are property
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